Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Microbiology > Lectures 4-6 > Flashcards

Lectures 4-6 Flashcards

1
Q

antibiotics

A

naturally occurring antimicrobial drugs

used in the treatment and prevention of bacterial infections
may either kill or inhibit the growth of bacteria

e.g. streptomycin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

aminoglycoside

A

antibiotics containing amino sugars
contain glycosidic bonds
eg. kanamycin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

semi-synthetic antibiotic

A

modified naturally occurring antibiotic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

macrolides

A

contain lactone rings

e.g. erythromycin
Broad-spectrum antibiotic
targets the 50S subunit of ribosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

tetracycline

A

contains 4 rings

widespread medical use in humans and animalsBroad-spectrum inhibition of protein synthesis
Inhibits functioning of 30S ribosomal subunit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

quinolones

A

synthetic anitibiotic

causes inhibition of DNA gyrase by binding to the A subunit of DNA gyrase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

most important group of antibiotics

A

beta-lactam

includes: penicillins, cephalosporins, and cephamycins

Over half of all antibiotics used worldwide are beta-lactam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

penicillin

A

Alexander Fleming
Primarily effective against Gram-positive bacteria

Some synthetic forms are effective against some Gram-negative bacteria
Target cell wall synthesis

bacteriolytic effect on bacterial growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

3 effects of antibiotics on bacterial growth

A

bacteriolytic - inhibit cell wall synthesis e.g. penicillin

bacteriocidal - kill bacteria

bacteriostatic - slow bacterial growth/reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how do you measure antibacterial activity

A

liquid culture poured onto agar plate

discs containing antimicrobial agents placed onto agar

incubated 24-48hrs

culture will show susceptibility to agents if bacterial growth inhibition seen around discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why might antibiotics cause adverse side effects

A

they act on similar eukaryotic structures and processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

vancomycin

A

inhibits cell wall biosynthesis

however poor bioavailability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

minimising resistance

A

only use antibiotics when needed and correctly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how may antibiotic resistance form

A

Organism lacks structure the antibiotic inhibits
Organism is impermeable to antibiotic
Organism can inactivate the antibiotic
Organism may modify the target of the antibiotic
Organism may be able to pump out the antibiotic (efflux)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

examples of essential processes that antibiotics target

A

central dogma - transcription/translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

folic acid

A

precursor for DNA

bacteria can’t make their own - need to obtain it
they interfere with folic acid synthesis and prevent DNA forming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

EFB

A

endospore forming bacteria

e.g. bacillus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

taxonomy

A

the science of classification

  • identifies relationships between groups of organisms
  • universal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

taxa

A

categories of organism

  • relatedness is a result of evolutionary history or phylogeny
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

prokaryotes

A

no membrane bound nucleus or organelles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

gram positive bacteria

A

thick peptidoglycan layer

positive stain test - stains crystal violet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

gram negative bacteria

A

do not retain violet stain due to thin peptidoglycan layer
counter stained with safranin
sugar chains off outer membrane

23
Q

further divisions of gram +ve bacteria

A

Firmicutes - Low G+C (<30% GC)

Actinobacteria - High G+C (60/70% GC)

24
Q

firmicutes

A

low g+c gram +ve bacteria

e.g.
lactobacilalles
- lactobacillus (used in fermented products e.g. yoghurt)
- streptococcus (medically relevant)
bacilalles
- staphylococcus (boils)
- bacillus (rod-shaped, endospore forming)
clostridiales
- clostridium (rod-shaped, form endospores,medically important)

tolerant to low pH
acid by-products e.g. lactic acid, butyric acid, acetic acid

25
actinobacteria
high g+c gram +ve bacteria actinomycetales - Actinomyces (filamentous, some human pathogens, facultative anaerobe, soil ecology) - Frankia (symbiotic nitrogen fixers) - Streptomyces (filamentous, produce antibodies and spores called e.g. aminoglycosides, tetracyclines) similar appearance to fungi
26
proteobacteria
gram -ve - metabolically diverse - many environmental habitats e.g. soil, aquatics - many are nitrogen fixing
27
examples of proteobacteria
Alpha - α - Bradyrhizobium/Rhizobium (Form symbiosis with plants and fix nitrogen to ammonia) Beta - β - Neisseria (Characteristic diplococci, medically important, meningitis) Gamma - γ - Shigella/ Salmonella (Responsible for serious food poisoning) - Escherichia (Common inhabitant of intestinal tract but uncommon pathogen (O157:H7) Very important research tool e.g. E. coli) ``` Delta - δ - Campylobacter (Highly motile bacillus, curved Medically important species, foodborne disease – C. jejuni) - Helicobacter (Has multiple flagella Cause of stomach ulcers - H. pylori) ``` Epsilon - ε
28
why do we know so much about bacteria
easy to culture and grow in a lab
29
Gamma/γ proteobacteria
most common subdivision | contains most pathogens
30
how can you study non-culturable bacteria
Fluorescent oligonucleotides that bind specific DNA
31
FISH
fluorescent in situ hybridisation different coloured oligonucleotides match different 16S rRNA sequences can identify complexity of bacterial group
32
ecosystem
sum of all organisms and abiotic factors in an environment | contains many different habitats
33
abiotic
non-living physical and chemical
34
symbiosis
mutualism - both species benefit commensalism - one species benefits, one not affected
35
syntrophy
Two or more organisms catabolising a nutrient that can not be catabolised by one on its own
36
species richness
total number of species in an ecosystem
37
species abundance
the proportion of each species in an ecosystem
38
why do bacteria grow more quickly in a lab
no limited resources of nutrients nutrients are localised and not widely distributed they dont have to grow in mixed populations
39
photic zone
200m below surface archaea more suited to environment below photic zone
40
pelagic zone
nutrient poor
41
root nodule bacteria symbiosis with legumes
rhizobia (gram -ve) ammonia created from atmospheric nitrogen ammonia used by plant to make amino acids and nucleotides plant provides bacteria with sugars
42
role of gut microbiome in obesity
more methanogens means low H2 and more fermentation (CH4 produced) - more obesity
43
pH in the gut
low pH2 in stomach | increases to pH7 by colon
44
baltmore method
method of classification of viruses | based on mode of replication and genome type
45
5 virus taxonomic groups
``` order (-virales) family (-viridae) subfamily (-virinae) genus (-virus) species ```
46
viruses
non-living entities extracellularly exist as virions utilise host proteins upon infection for their propagation
47
nucleocapsid
nucleic acid | surrounded by a capsid (membrane made up of capsomers)
48
virophage
virus that infects the mimivirus - recently discovered
49
bacteriophage
virus of bacteria
50
lifestyle of bacteriophage
1. virion attaches to host bacteria 2. viral DNA penetrates and enters host, protein coat remains outside 3. synthesis of nucleic acid and protein 4. assmebly and packaging 5. release/lysis of newly formed virions
51
temperate bacteriophage lifestyle
lytic pathway - viral DNA replicates - protein coats are synthesized - viral particles burst out of cell during lysis - occurs if cro gene dominates lysogenic pathway - viral genome (prophage) enters into host chromosone - viral DNA replicated with host DNA - occurs if cl gene dominates
52
lytic pathway stages
1. transcription and translation of N and cro from the P 2. longer transcripts are made with help of N protein (N binds RNA polymerase to read termination sequences allowing further transcription) 3. stimulation of phage structural gene synthesis by Q protein
53
lysogenic pathway stages
1. lambda repressor protein (cl) synthesis from P 2. cl and cro compete for transcription 3. lambda repressor protein (cl) blocks synthesis from lytic pathway genes 4. lysogenic pathway begins when cl is transcribed and translated

Microbiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions